Charge disproportionation in the spin-liquid candidate κ-(ET)2Cu2(CN)3 at 6 K revealed by 63Cu NQR measurements
Charge disproportionation in the spin-liquid candidate κ-(ET)2Cu2(CN)3 at 6 K revealed by 63Cu NQR measurements
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DOI：
10.1103/physrevresearch.2.042023
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发表时间：
2020-10-30
影响因子：
4.2
通讯作者：
Furukawa, Y.
中科院分区：
文献类型：
--
作者：
Kobayashi, T.;Ding, Q-P;Furukawa, Y.
自旋液体候选物kappa-（ET）（2）Cu-2（CN）（3）[ET：bis（ethylenedithio）tetrathiafulvalene]在非常低的温度下不显示磁有序，但在6 K时显示出神秘的异常。所谓的6-K异常的起源仍在争论中。我们进行了核四极共振（NQR）测量的铜网站的绝缘层，这是敏感的电荷动力学不同于传统的自旋1/2核磁共振（NMR）。本次快速通讯的主要发现是，在6 K下观察到Cu-63 NQR的核自旋-晶格弛豫速率T-1（-1）的尖峰行为，而C-13和H-1 NMR的T-1（-1）没有显示出明显的异常。这种行为可以被理解为与ET层中的电荷极化相关的二级相变。
The spin-liquid candidate kappa-(ET)(2)Cu-2(CN)(3) [ET: bis(ethylenedithio)tetrathiafulvalene] does not exhibit magnetic ordering down to a very low temperature, but shows a mysterious anomaly at 6 K. The origin of the so-called 6-K anomaly is still under debate. We carried out nuclear quadrupole resonance (NQR) measurements on the copper sites of the insulating layers, which are sensitive to the charge dynamics unlike conventional spin-1/2 nuclear magnetic resonance (NMR). The main finding of this Rapid Communication is that the observation of a sharp peak behavior in the nuclear spin-lattice relaxation rate T-1(-1) of Cu-63 NQR at 6 K while T-1(-1) of both C-13 and H-1 NMR show no clear anomaly. This behavior can be understood as a second-order phase transition related to charge disproportionation in the ET layers.